1. Field of the Invention
The present invention relates to an apparatus and method for the low energy flash-like vaporization of liquids. The resulting vaporized liquid is released into the atmosphere in the form of a condensation aerosol, giving rise to a visible plume, mist or cloud. The resulting plume, mist or cloud can rapidly dissipate. Vaporization is occasioned in a geometrically small device capable of producing vaporized liquid that varies little in composition in comparison to the starting liquid feed to the device. The apparatus and methods are primarily directed towards the treatment of small areas for residential air fragrancing, odor elimination, treatment of insects or pests, air sanitization, air and surface antibacterial or antimicrobial treatment, administration of personal pharmaceuticals or medicaments, as well as for other ambient air or surface modification by way of gas, vapor or droplet distribution.
2. Discussion of the Related Art
Traditional techniques for introducing liquids into the atmosphere for fragrancing or air treatment include such methods and devices such as potpourri, reed sticks, incense and warming stoves. Potpourri, which is dried, naturally fragrant plant material, is typically used to fragrance homes. With ambient air motion, fragrance wafts from the dried material to permeate room environments. Reed sticks are relatively new products in which fragranced compositions wick up a porous cellulosic shaft and are emitted into the room environment. Wood and bamboo are examples of often-used cellulosic shafts. Incense involves the use of aromatic, biologically derived materials. A fragrant smoke is released from the incense material upon burning, which is characteristically accompanied by smoke and soot. Warming stoves typically heat fragranced solids, oils or solutions by candles or other external means up to the smoke point to release fragrancing components into the ambient air. Again, such practice is often accompanied by smoke and soot.
More recent automatic techniques that are available for fragrancing or treating ambient air include devices such as: heated wick diffusers and products of the so-called “plug-in” variety; vibrating atomizers; and ultrasonic devices. Examples of heated wick and plug-in diffusers include: Glade® PlugIns®, sold by S.C. Johnson & Son, Inc., Racine, Wis.; Airwick® Scented Oil Warmers, sold by Reckitt Benckiser, Parsippany, N.J.; and Febreze® NOTICEables™, sold by Procter & Gamble, Cincinnati, Ohio; among others. An example of a vibrating atomization mesh or plate that employs a piezoelectric technique is the Glade® Wisp®, sold by S.C. Johnson & Son, Inc., Racine Wis. Essentially, this technique employs a vibrating element to shake liquid feed into the atmosphere. One problem associated with this technique is the poor mechanical reliability of the vibrating parts. Aside from the device being prone to breakage during post-manufacture transport before reaching consumers, the mechanical elements appear to not be very robust and often break, shortly before or after use has commenced. The lack of robustness of the moving parts thus leads to average shorter product life for piezoelectric devices. Material can also build up on the vibrating element, leading to inefficient operation of the device. The latter results in greater energy being required to disperse the feed liquid and can result in poor fragrance dispersal or none whatsoever. An example of a pump atomizer is the Mr. Steam® Aromaflo® Oil Injector System available from Sussman-Automatic Corporation, Long Island City, N.Y. Examples of ultrasonic devices used for fragrancing air include: The Ultrasonic Fragrance Machine, from Stiers, GmbH of Aschheim, Germany; Ultrasonic Air Fragrance for Home or Car, sold by Ultronix Products Ltd., China; Ultrasonic Aromatherapy Essential Oil Atomizer, sold by Wedian Technology Co., Ltd., China; as well as the MABISMist™II Ultrasonic Nebulizer, an ultrasonic water vaporizer from MABIS® Healthcare.
Problems with several of the known techniques and devices mentioned above include: 1) difficulties with accurate control of the amount of material being vaporized or otherwise introduced into the air; 2) inability to view, sense, or perceive the liquid or other material as it is being vaporized; 3) reproducibility of droplet size, agglomeration of droplets, and like issues; and 4) habituation of scent over relatively short periods of time such as hours or days. Habituation as used herein is understood to pertain to a phenomenon in which an individual becomes sufficiently accustomed to a particular fragrance after a period of exposure such that the individual becomes unable to discern its presence; 5) the phenomenon of “rain out” over time, where the term rain out as used herein is understood to refer to the tendency for the deposition of aerosolized particles onto a surface; and 6) segmentation of the formula, which disrupts the so-called “scent fidelity” by the dispensing mechanism. Segmentation occurs especially with heated wick diffusers, whereby the composition of the vapor poorly matches the composition of the feed liquid. The vapor composition changes over time as lighter formula elements are vaporized initially and heavier formula components are vaporized thereafter.
Recently, in addition to the efficiency, delivery and aesthetics of fragrance and other actives, particular aspects of liquid dispersal devices have received even greater scrutiny. As increasing numbers of consumers have begun using these products, in particular the more recent automatic techniques, emerging issues have captured the attention of regulatory groups, such as: 1) energy utilization; 2) reliability of the device; 3) ability of the technique to faithfully convey to the atmosphere a composition as similar as possible to that of the original liquid, insecticide composition, fragrance, pharmaceutical preparation, medicament; and so forth; 4) the use of propellants and solvents for dispersal of vaporized liquid that are detrimental to the environment; and 5) the need for quiet and discrete operation. Each of the prior art methods described above exhibits one or more of the aforementioned shortcomings. A summary of the prior art liquid dispersal methods and associated disadvantages that have been discussed herein are summarized in Table 1:
TABLE 1Summary of Perceived or Known Disadvantages of Competitive TechnologiesCompetitive TechnologyPerceived technology weaknessHeated Wick DiffusersNo visual signal to indicate that it is working.Provides constant dose, causing rapid habituation such that thefragrance may not be perceived within hours or days.Top notes evaporate out ahead of bottom notes, such that fragrancecharacter changes over time, for example, over thecourse of a month.Significant use of energy over lifetime of the device; about 1.5to 2 kilowatt-hour per month.The electrical heating element is constantly hot during use,which can potentially raise safety issues.Scented Reed DiffusersNo visual signal to indicate that it is workingPoor transmission of fragranceIntermittent manual attention required to periodically rotatethe reeds.Bottles can be tipped over and contents spilled; no secondaryfragrance containment.Fragrance oil warmersCan emit soot and smoke that is reminiscent of incenseRelatively low fragrance impact, unless operated at temperaturesthat are unsafe to the touch. The oils that are typicallyused with such fragrance warmers are not very aromatic andthe scent is highly localized.Significant energy use, typically similar to or greater than theheated wick diffusers; about 1.5 to 2 kilowatt-hour per month.Device must be periodically checked during operation forrefilling and monitored for overheating. Consequently, potentialdanger if device permitted to go dry.Propellant-BasedAutomated and manual aerosol cans that are used in institutionalDispensersand industrial (I&I) settings are disadvantageous fromenvironmental perspectives.Formulations are typically comprised of environmentallyharmful propellants.Propellants and/or solvents in liquid formulations often resultin emanation of unpleasant or undesirable scents.Aerosol droplets can rain out, rapidly reducing fragranceimpact.Piezoelectric devicesRelatively short lifetime, due either to fouling from organiccompounds, malfunction through poor manufacturing, or relativelyshort lifetime of vibrating components.Pumped Atomizers andVarious devices are generally bulky and/or noisy.NebulizersOther devices tend to be messy in generating large quantitiesof condensation.
As noted above, there are a number of disadvantages associated with prior art air treatment devices. It is therefore desired to provide devices for various kinds of air treatment that overcome these disadvantages. It is also desirable to require less constant monitoring and have minimal human intervention with air treatment devices, unlike current devices such as those that involve aerosol cans, candles, fragrance warmers, reed diffusers, and the like. Furthermore, certain devices that contain moving parts, such as piezoelectric devices or pumps are inherently given to breakdown through malfunction or innate lifetime. Finally, heated wick plug-in diffusers use significantly more energy to deliver desired doses of material over extended periods, due to highly inefficient heating of their wicking components to volatilize the organic compounds.